This invention relates generally to the field of loading tape carriers into a machine for recording on or playing back from, the tape, and more particularly to a mechanism suited for loading tape cartridges of the internal belt-drive type wherein the tape must be pulled from the cartridges and wrapped around a suitable transducer. The mechanism can also be used with conventional tape cartridges or cassettes and is not limited to use solely with internal belt-drive type cartridges.
One cartridge of the internal elastic-belt-drive type is depicted in U.S. Pat. No. 3,692,255 dated Sept. 19, 1972 by R. A. Von Behren. In a cartridge of this type the tape is carried by two reels referred to generally as a "supply" reel and a "take-up" reel. The drive for the reels is provided by an "endless" elastic belt which contacts the tape on both reels with the result that by driving the belt, both the reels are also driven.
It is known in the art, when recording on and playing back from a tape, to draw a loop of tape from a conventional cartridge (i.e. not of the internal belt-drive type) and to wrap the tape around (less than 360.degree.) a rotating transducer. U.S. Pat. No. 3,860,960 dated Jan. 14, 1975 by T. Akamine depicts one such system. Many other systems for withdrawing tape from cartridges and cassettes (referred to generally as tape carriers) exist in the art. The following U.S. patents depict but a few of those systems, and attention is directed to them: U.S. Pat. No. 4,045,820 dated Aug. 30, 1977 by T. C. J. L. Staar; U.S. Pat. No. 4,092,686 dated May 30, 1978 by G. Schulz; and U.S. Pat. No. 4,258,399 dated Mar. 24, 1981 by K. Iijima et al. IBM Technical Disclosure Bulletin Vol. 9, No. 8, January 1967 in an article on page 968 entitled "Automatic Tape Threading" by R. B. Johnson et al discloses yet another scheme for withdrawing tape from a cartridge.
These techniques of withdrawing tape from a cartridge work well with conventional cartridges, but pose problems when employed with cartridges of the internal belt-drive type. The reason for the difficulties with the internal belt-drive type cartridges is that it is difficult to withdraw the tape from that type of cartridge without damaging the tape. With an internal belt-drive type cartridge, when the tape is removed from one reel, the drive belt moves and consequently the other reel is also moved to accept tape; in other words, no appreciable slack can normally appear in the tape; certainly not enough slack to permit a loop of sufficient size to engage a transducer.
One solution to this problem is depicted in U.S. Pat. No. 4,275,424 dated June 23, 1981 by A. R. Maxey. The solution, according to that patent, is to provide a special cassette that holds a length of the tape proud of the reels in every access of a transducer. When the cassette is not in active use, a lever arm applies tension to the exposed length of tape, thereby partially withdrawing it into the cassette. When in active use, (i.e. in engagement with a transducer) the lever arm releases the tape allowing it to contact the transducer. The facts that the cassette includes a "cut-out" portion and that the tape contacts the transducer significantly less than 180.degree. of tape turn also play a factor in this solution (see column 1, lines 48 and 49 of that patent).
One major drawback to such a solution is the need to use a special cassette.
It is one object of the present invention to withdraw tape from an internal belt-drive cartridge of standard manufacture (one example being a model DC-300A cartridge manufactured by the Minnesota Mining and Manufacturing Co., commonly referred to as 3M) and to wrap the tape so withdrawn around (less than 360.degree.) a transducer.